1. Field of the Invention
The present invention relates to the shape of a face of a wood-type golf club head.
2. Description of the Related Art
In order to understand how to increase of a distance or carry the ball hit by a club, the structure and the material of a wood club head have been investigated. In the background art, particularly, with respect to a face acting as a hitting surface, the hardness of the material has been actively increased so as to increase the repulsion force. Since there is a limit in the weight of the head, however, the development of the material has reached an end (a limit) with titanium and an alloy thereof. At this point, however, it can be gathered that there is a movement of reconsideration of utilization of the repulsion force based on the flexure of the face at the time when a ball is hit.
Setting the thickness of a face to be extremely thin in order to increase the flexure of the face has become a limit substantially from a point of view of durability. Further, although there has been proposed such a method that a ring-like groove is formed in a face at its peripheral edge portion so that the flexure is increased by the transformation of the groove, there is generated a fear in the durability of the groove portion if it is intended to obtain sufficient repulsion force.